Switching apparatus for telephone systems



March 23, 1954 H. SENGEBUSCH 2,673,247 SWITCHING APPARATUS FOR TELEPHONESYSTEMS Original Filed Dec. 18, 1947 5 Sheets-Sheet l INVENTOR. HansSengebusch as-LA,

Affys.

March 1954 H SENGEBUSCH swncamc APPARATUS FOR TELEPHONE SYSTEMS- 5Sheets-Sheet 2 Original Filed Dec. 18, 1947 g INVENTOR.

Hans Sengebusch BY M WM March 23, 1 H. SENGEBUSCH SWITCHING APPARATUSFOR TELEPHONE SYSTEMS 5 Sheets-Sheet 3 Original Filed Dec. 18, 1947 E: 52 R B March 33. .1954 H. SENGEBUSCH SWITCHING APPARATUS FOR TELEPHONESYSTEMS 5 Sheets-Sheet 4 Original Filed Dec. 18 1947 com com

INVENTOR. Hans Sengebusch MAM March 23, 1954 H. SENGEBUSCH 2,673,247

SWITCHING APPARATUS FOR TELEPHONE SYSTEMS Original Filed Dec. 18, 1947 5Sheets-Sheet 5 225 FIG. 7 225 m V i 224 FIG 8 I 224 1 FIG. 9

@ (:DCE INVENTOR' Y Hans Sengebusch Patented Mar. 23, 1954 SWITCHINGAPPARATUS FOR TELEPHONE SYSTEMS Hans Scngebusch, Chicago, 111., assignorto Automatic Electric Laboratories, Inc., Chicago, 111., a. corporationof Delaware Original application December 18, 1947, Serial No. 792,509,now Patent No. 2,604,541, dated July 22, 1952. Divided and thisapplication October 29, 1951, Serial No. 253,585

6 Claims.

The present invention relates to switching apparatus for telephonesystems and more particularly to such apparatus of the so-called X-Ymotions or flat type. This application is. a division of the copendingapplication of Hans Sengebusch, Serial No. 792,509, filed December 18,1947, now Patent No. 2,604,541, granted on July 22, 1952.

It is an object of the present invention to provide an improvedarrangement of a plurality of automatic switches, each of the X-Ymotions or flat type, and a contact bank assembly commonly associatedtherewith.

Another object of the invention is to provide a contact bank assembly ofimproved and simplified construction and arrangement accommodating readyassembly and disassembly of the contact bank units incorporated therein.

A further object of the invention is to provide an improved combinationcontact bank unit and terminal structure therefor.

Further features of the invention pertain to the particular arrangementof the contact bank units in the assembly and the elements of eachcontact bank unit, whereby the above-outlined and additional operatingfeatures thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification taken inconnection with the accompanying drawings, in which Figures 1A and. 1B,taken together, are a plan view, partly broken away, of switchingapparatus constructed and arranged in accordance with the presentinvention; Figs. 2A and 2B, taken together, are a front elevationalview, partly broken away, of the switch ing apparatus shown in Figs. 1Aand 13; Figs. 3A and 3B, taken together, are a plan view, partly brokenaway, of the switching apparatus shown in Figs. 1A and 1B, illustratingcertain elements disposed below the base plate thereof; Fig. 4 is afragmentary lateral sectional view, taken in the direction of the arrowsalong the line 4-4 in Fig. 1B, illustrating the arrangement of theprimary and secondary carriages of the switching apparatus shown inFigs. 1A and 13; Fig. 5 is a bottom view of a fragmentary centralportion of the base plate of the switching apparatus shown in Figs. 1Aand 1B, illustrating the cooperation between the primary carriagethereof and an associated set of control contacts; Fig. 6 is afragmentary inverted front elevational view, taken in the direction ofthe arrows along the line 6-6 in Fig. 5, of the central portion of thebase plate of the switching apparatus and the associated elements; Fig.7 is a plan view of a contact bank and terminal unit associated with twoof the main wipers supported by the secondary carriage of the switchingapparatus shown in Figs. 1A and 1B; Fig. 8 is a fragmentary end view ofthe unit shown in Fig. 7; and Fig. 9 is a fragmentary front view of theunit shown in Figs. 7 and 8.

Referring now more particularly to Figs. 1A, 13, 2A and 2B of thedrawings, the switching apparatus there illustrated comprises switchingmechanism IMA, contact bank structure 200 and supporting structure,including two vertically extending and longitudinally spaced apartelements Zlla and 2H?) and two horizontally extending and longitudinallyspaced apart elements M2 and H3. The switching mechanism IUBA comprisesa longitudinally extending base plate 10 provided with a downwardlyturned front flange Illa and a rearwardly extending apron Mb. The baseplate In is supported upon the horizontal elements 212 and 2I3 and therear edge thereof abuts the front edges of the vertical elements 2lla.and Zllb, the apron [0b being arranged between the longitudinally spacedapart vertical elements Mia and 2!); whereby the normal position of thebase plate I0 is accurately located by the vertical elements 21 la and 2l lb upon the horizontal elements H2 and M3 so that the switchingmechanism [00a occupies a predetermined and exact position with respectto the associated contact bank 200. The base plate In is normallyrestrained in its normal position by two guiding devices 2M secured tothe front flange Illa thereof respectively adjacent to the left-hand endand to the right-hand end thereof and respectively cooperating with thelower surfaces of the horizontal elements 212 and M3. Thus it will beunderstood that the base plate It] may be readily removed with respectto the supporting structure, including the vertical elements 2 I la and2] lb and the horizontal elements M2 and H3, merely by sliding it towardthe front away from the contact bank 200. Accordingly, the switchingmechanism [00a may be readily placed upon and removed from theassociated supporting structure for purposes of inspection and repair.

The contact bank 200 is of the ZOO-point or line type, each lineincluding a positive conductor, a negative conductorand two controlconductors; whereby the contact bank 2% comprises 800 individual contactstrips accessible to the tact strip type extending vertically in thecontact bank 200. The contact bank 200 is accessible to a number ofswitching apparatus, including the switching apparatus 100A, carried bythe supporting structure in a vertical tier; whereby the contact bank200 serves as a multiple between the different switching apparatus formarking purposes.

All of the elements of the switching mechanism was are secured to thebase plate so that they are properly positioned with respect to thecontact bank 200 when the base plate I0 is positioned upon thesupporting structure as previously explained. Specifically, theswitching mechanism 100A comprises contact controlling mechanism in theform of eight main individual wipers I, 2 and 3, 4 and 5, 6 and l, 8;the individual wipers I, 3, and I constituting a first wiper set havingaccess to 100 lines, and the "individual wipers 2, 4, 6 and 8constituting a second wiper set having access to 100 lines.Specifically, the wipers l and 2 may comprise positive line wipershaving access to the positive line conductors of the two groups of 100lines each; the wipers 3 and 4 may comprise negative line wipers havingaccess to the negative line conductors of the two groups of 100 lineseach; the wipers 5 and 6 may comprise first control wipers having accessto the first control conductors of the two groups of 100 lines each; andthe wipers l' and B may comprise second control wipers having accesstothe second control conductors of the two groups of 100 lines each.

The two wiper sets are capable both of selective primary or longitudinalmovement from the left toward the right and of selective secondary orlateral movement from the front toward the rear. Specifically, the twowiper sets are capable often individual steps of longitudinal movementand of ten individual steps of lateral movement. Since each of the foursections of the contact bank 200 are respectively associated with twocorresponding ones of the individual wipers, each of the 200 lines isaccessible to the two wiper sets.

ment is imparted to the two wiper sets, the four corresponding contactunits 201 are selected thereby; and when a given number of steps oflateral movement is imparted to the two wiper sets; eight individualcontact strips comprising two lines in the four selected contact units20! are selected. Accordingly, each combination longitudinal and lateralposition of the two wiper sets corresponds to two individual lines inthe contact bank 200 respectively selected by the two wiper sets.Finally, the first wiper set comprising the individual wipers I, 3, 5and I are connected by a first set of flexible conductors, not

shown, to a terminal set 84 carried on the lefthand front centralportion of the base plate It]; and the second wiper set comprising theindi vidual wipers 2, 4, 6 and 8 are connected by a second set offlexible conductors, not shown, to a terminal set 83 carried on theright-hand front central portion of the base plate l0.

Considering now the construction of the switching mechanism IOOA ingreater detail, and

Moreover, when a given number of steps of longitudinal movebase plate l0carries a longitudinally extending stationary guide bar 95 disposedadjacent to the front edge thereof and spaced thereabove. Alongitudinally slidable primary carriage I6 is supported upon the guidebar 95 adjacent to the left-hand and central portions thereof; whichprimary carriage l6 terminates in two longitudinally spaced apart andrearwardly extending guide rails IGa and [6b. The extreme outer ends ofthe guide rails 16a and lBb are secured to a longitudinally extendingsubstantially L-shaped bracket 12 by two rivets 13a and 13b; the bracket12 comprising a vertical ledge 12a and a horizontal ledge 12b disposedadjacent to the rear edge of the base plate ID. A laterally slidablesecondary carriage I5 is supported upon the guide rails 16a and 18b; thesecondary carriage I5 comprising two downwardly and inwardly turned lugs2l5a arranged in laterally spaced apart relation with respect to eachother on the lefthand side thereof and embracing the associated flangeof the guide rail lBa and two downwardly and inwardly turned lugs 21%arranged in laterally spaced apart relation with respect to each otheron the right-hand side thereof and embracing the associated flange ofthe guide rail lBb. A substantially U-shaped bracket 62 is secured tothe left-hand side of the secondary carriage I5 by two rivets 80a andterminates in two flanges 62a and 62b; the flange 62a supporting themain wipers I and 2 in longitudinally spaced apart relation with respectto each other by virtue of an arrangement including a plurality ofintervening insulating strips 64 and a plurality of rivets 80w; and theflange 62b supporting the main wipers 3 and 4 in longitudinally spacedapart relation with respect to each other by virtue of an arrangementincluding a plurality of intervening insulating strips 65 and aplurality of rivets 80:0. Similarly, a substantially U -shaped bracket63 is secured to the right-hand side of the secondary carriage l5 by tworivets tab and terminates in two flanges 53a and 63b; the flange 63asupporting the main wipers 5 and 6 in longitudinally spaced apartrelation with respect to each other by virtue of an arrangementincluding a plurality of intervening insulating strips 66 and aplurality of rivets 8M1; and the flange 63b supporting the main wipers 1and 8 in longitudinally spaced apart relation with respect to each otherby virtue of an arrangement including a plurality of interveninginsulating strips 61 and a plurality of rivets 802.

The vertical ledge 12a of the bracket 12 carries four longitudinallyspaced apart pins upon which four insulating bushings 68, 69, 10 and 1|are arranged; the bushings 68, 69, i0 and H being disposed between therespective pairs of main wipers I, 2 and 3, 4 and 5, 5 and I, 8 in orderto maintain the individual wipers of each pair out of contact with eachother when they occupy their fully retracted positions toward the frontof the base plate l0.

The primary carriage l6 comp-rises a normal longitudinal position andmay be moved step by step therefrom in the longitudinal direction fromthe left toward the right as previously noted; and in order toaccomplish this primary movement of the primary carriage iii, anarrangement including a primary magnet II is provided. The primarymagnet H is suitably secured to the rear left-hand portion of the baseplate H1 and comprises magnetic structure including an armature llpivotally mounted upon a pin l8 and normally biased in the clockwisedirection referring to Figs. 1A, 113, 2A, 2B, 3A, 3B and 4, the aboutthe pivot pin 48 by an arrangement including a coil spring 22 extendingbetween the extreme outer end of the armature I1 and a lug 28 secured tothe front flange Illa oi the base plate Ill. A pawl I9 is pivotallymounted upon a pin 20 carried on the extreme outer end of the armatureI1 and cooperates with a ratchet 23 secured to a primary bar Ilia formedintegrally with the primary carriage It by a plurality of pins 9adjacent to the lefthand end thereof. The pawl I9 is biased in thecounterclockwise direction into engagement with the ratchet 23 by a coilspring 2| extending between the armature I! and the pawl I9. The primarycarriage it is normally restrained in its normal longitudinal position,the primary bar I60: engaging a stop 39 carried by the upper surface ofthe base plate I adjacent to the front edge thereof, by an arrangementincluding a coil spring I36 disposed below the base plate I0, one end ofthe coil spring I35 being secured to a pin I39a carried by the undersurface of the base plate I ii and the other end of the coil spring I38being secured to a fixture I991) carried by the primary carriage I6 andprojecting thr u h a slot, not shown, formed in the base plate Ill belowthe primary carriage I9.

When the winding of the primary magnet I I is energized the armature I?i attracted and rotated in the counterclockwise direction about thepivot pin I9 against the bias of the coil spring 22 causing the pawl I9engaging the ratchet 23 to drive the primary bar Ito and the primarycarriage I6 away from its normal longitudinal position one step towardthe right away from the stop 30 and against the bias of the coil springI35. When the ratchet 23 is thus operated by the pawl I9, a detent 24secured to the front flange Illa of the base plate Ill enters theassociated tooth thereby restraining the ratchet 23 in its operatedposition against the bias of the coil spring I36. Subsequently when thewinding of the primar magnet II is deenergized, the armature I1 isreleased and rotated in the clockwise direction about the pivot pin I8by the coil spring 22, whereby the pawl l9 engages the next tooth in theratchet 2-3 thereby conditioning the pawl I9 to drive the ratchet 23,the primary bar L Ida and the primary carriage it an additional steptoward the right. When the primary carriage I6 is driven away from itnormal longitudinal position one step toward the right, the two wipersets are brought into longitudinal alignment with respect to the twocorresponding first groups of ten lines in the two IOU-line groups inthe associated contact bank 299. Thus it will be understood that byenergizing the winding of the primary magnet II a number of times theprimary carriage I is driven a corresponding number of steps away fromits normal longitudinal position toward the right in order to cause thetwo wiper sets to select the two corresponding groups of ten lines inthe two IOO-line groups in the associated contact bank 299.

The secondary carriage I5 comprise a normal lateral position and may bemoved step by step therefrom in the lateral direction from the fronttoward the real. as previously noted; and in order to accomplish thissecondary movement of the secondary carriage I5 an arrangement includinga secondary magnet I2 is provided. The secondary magnet I2 is suitablysecured to the rear right-hand portion of the base plate I9 andcomprises magnetic structure including an armature 25 pivotally mountedupon a pin 85 and normally biased in the counterclockwise directionabout th pivot pin 66 by an arrangement including a coil spring 89extending between the extreme outer end of the armature and a lug 90secured to the front flange Illa of the base plate I9. A pawl 87 ispivotally mounted upon a pin 9i carried on the extreme outer end of thearmature 85 and cooperates with a ratchet 93. The pawl 81 is biased inthe clockwise direction into engagement with the ratchet 93 by a coilspring 99 extending between the armature 85 and the pawl 81. The ratchet93 is secured to a fixture 94 slidably mounted upon the guide bar- 95and supporting a secondary bar or rack 96 disposed below the guide bar95 and above the top surface of the base plate In. The extreme left-handend of the rack 96 carries a downwardly extending pin 99a disposed in alongitudinally extending guide slot, not shown, formed in the base plateIll. The rack 96 is normally restrained toward the right by a coilspring H4 disposed below the base plate I9, one end or the coil springII4 being secured to the pin 99a and the other end of the coil spring H4being secured to a pin, not shown, carried by the under surface of thebase plate Ill.

The rack 96 cooperates with two gears I02 and H39 respectively rotatablymounted upon two longitudinally spaced apart upstanding pins I 04 andI95 carried by the base plate l9. Also the upper surface of the baseplate It] carries a longitudinally extending bracket I98 provided withan upstanding fiange ms and two longitudinally spaced apart andforwardly extending racks I96 and I9! respectively meshing with thegears I02 and I03. The bracket I93 is retained in place upon the uppersurface of the base plate I t by an arrangement comprising twosubstantially inverted U- shaped guide members I20 and I2I respectivelyreceiving the racks I06 and IE1, the guide members I 29 and I2i beingretained in place upon the upper surface of the base plate It] by aplurality of screws IZlia and I2Ia, respectively. Also two laterallyextending guide elements '16 and I1 disposed in longitudinally spacedapart relation are secured to the upper surface of the base plate It bya plurality of screws 19a and 'I'Ia, respectively. The guide elements I9and TI respectively cooperate with two outwardly projecting lugs I9 and78, respectively, formed on the left-hand and on the right-hand sides ofthe bracket I99, the lug l9 and 78 respectively extending belowoverhanging flanges formed on the guide elements I6 and 71.

As previously noted the rack 99 is normally restrained in its extremeright-hand position by the coil spring II 4; whereby the meshing gearsI92 and H13 coact with the meshing racks Iilt and I9! to restrain thebracket 298 in its retracted position toward the front of the base plateto. The flange 92?) formed on the righthand side of the bracket 62 isprovided with a downwardly projecting bifurcated element providing aslot, not shown, embracing the upwardly turned flange I99 formed on thebracket I 03; and likewise the flange 930, formed on the lefthand sideof the bracket 63 is provided with a downwardly projecting bifurcatedelement providing a slot IIIJ, shown in Fig. l, embracing the upwardlyturned flange I89 formed on the bracket I98. Accordingly, the bracketlfi8 restrained in its normal lateral position as pointed out above alsorestrains the brackets 62 and I53 toward the front of the base plateIll; whereby the secondary carriage I5 supporting the brackets 92 and 63is restrained in its normal lateral position toward the front of thebase plate l0.

When the winding of the secondary magnet I2 is energized, the armature85 is attracted and rotated in the clockwise direction about the pivotpin 86 against the bias of the coil spring 89 causing the pawl 81engaging the ratchet 93 to drive the rack 96 away from its normallongitudinal position one step toward the left. The rack 96 meshing withthe gears I02 and I03 rotates them one step about the pins I34 and I85respectively; whereby the gears I02 and I03 respectively meshing withthe racks I06 and I01 move the racks I06 and I! and consequently thebracket I08 from its normal lateral position one step toward the rear ofthe base plate Ill. Since the upwardly turned flange I09 engages theslots mentioned formed in the downwardly projecting elements carried bythe flanges 62b and 33a of the brackets 62 and 63 secured to thesecondary carriage I5, the secondary carriage I is moved away from itsnormal lateral position one step toward the rear of the base plate I3;whereby the two wiper sets supported by the secondary carriage I5 aredriven into engagement with the first contact strips in the contactunits I previously selected by the longitudinal movement of the primarycarriage I8; whereby the two wiper sets mentioned select the first twocorresponding lines in the previously selected two groups of ten lineseach. When the ratchet 93 is thus operated by the pawl 81 against thebias of the coil spring I14, a detent I35) se- J cured to the frontflange llla of the base plate Ill enters the associated tooth therebyrestraining the ratchet 93 in its operated position against the bias ofthe coil spring H4. Subsequently, when the winding of the secondarymagnet I2 is deenergized the armature 85 is released and rotated in thecounterclockwise direction about the pivot pin 86 by the coil spring 39;whereby the pawl 81 engages the next tooth in the ratchet 93, therebyconditioning the pawl 8"! to drive the ratchet 93 an additional steptoward the left and consequently to drive the secondary carriage I5 anadditional step toward the rear of the base plate I0. Thus it will beunderstood that by energizing the winding of the secondary magnet I2 aplurality of times, the secondary carriage I5 is driven a correspondingnumber of steps away from its normal lateral position toward the rear ofthe base plate Ill in order to cause the two wiper sets to select twocorresponding lines in the two previously selected groups of ten lineseach.

Also the'switching mechanism IDOA comprises a fixture H9 secured to thefront central portion on the base plate In; which fixture H9 is providedwith an upstanding pivot pin H5 upon which an interlock lever II3 ismounted. The lever H3 is normally restrained in a clockwise directionabout the pivot pin I I5 by a coil spring IIB extending between thefixture H9 and the right-hand end of the lever II3. Also the lefthandend of the lever H3 is provided with a camming surface I I2 thatcooperates with a camming surface III provided on the rack 96. Finally,the extreme right-hand end of the lever H3 is provided with a latch Inthat cooperates with a series of openings Illa formed in the front edgeof the primary carriage I6 embracing the guide bar 95. Accordingly, whenthe primary carriage I6 occupies any one of its longitudinal operatedpositions, a corresponding one of the openings II'Ia formed in the frontedge thereof is brought into alignment with respect to the latch IIIcarried by the lever II3. Hence, when the rack 98 is subsequently movedfrom its nor- I mal longitudinal position toward the left, the

camming surface III formed thereon cooperates with the camming surfaceII2 formed on the lever I I3; whereby the lever I I3 is rotated in thecounterclockwise direction about the pivot pin i I5 against the bias ofthe coil spring I I8 causing the latch II'I to enter the aligned openingIlla formed in the front edge of the primary carriage I6. Accordingly,when the secondary carriage I5 is operated one step away from its normallateral position by the rack 96, the lever I I3 is operated in order tocause the latch II'I positively to lock the primary carriage I5 in itslongitudinal operated position.

Also the switching mechanism IIIOA comprises release mechanism includinga first release magnet I3 and a second release magnet I4. The firstrelease magnet I3 comprises magnetic structure secured to the upperright-hand portion of the base plate II]; and the second release magnetI4 comprises magnetic structure secured to the upper left-hand portionof the base plate Ill immediately forwardly of the primary magnet II.The magnetic structure of the first release magnet I3 comprises anarmature I22 pivotally mounted upon a pin I22a carried by the base plateIii; while the magnetic structure of the second release magnet I4comprises an armature I34 pivotally mounted thereon. Also the releasemechanism comprises a longitudinally extending r lease bar I23 disposedbelow the lower surface of the base plate II) and secured in place by anarrangement comprising a screw 2II threaded into an opening formed inthe base plate It] and disposed in a longitudinally extending slot I23aformed in the release bar I23 adjacent to the right-hand end thereof.The portion of the release bar adjacent to the left-hand end thereof issupported by a substantially U-shaped bracket 233 secured to the lowersurface of the base plate H! by an arrangement including a screw 223a,the bracket 223 loosely embracing the associated portion of the releasebar I23 to permit pivoting thereof about the screw 2II. Also the releasebar I23 is slidable longitudinally with reference to the screw 2II byvirtue of the arrangement of the elongated slot I23a formed therein. Therelease bar I23 is normally restrained in a normal position slid towardthe left and rotated in a counterclockwise direction about the screw 2IIby an arrangement including a coil spring I25 extending between theextreme left-hand end of the release bar I23 and a pin 2"; projectingdownwardly from the base plate Ill. The armature I22 of the first magnetI3 cooperates with a slot I24 formed in the release bar I23; and thearmature I34 of the second magnet I4 cooperates with a slot I35 formedin the release bar I23. Also a release dog I28 is pivotally mounted on apin I28a carried by the base plate It and provided with twosubstantially right-angularly disposed legs I21 and I29. The leg I29 ofthe release dog I28 projects substantially parallel to the front edge ofthe base plate I0 and toward the right behind the detent I3 3; while theleg I21 of the release dog I28 projects toward the rear of the baseplate Ill and is provided with a downwardly extending portion projectingthrough an opening I2'Ia formed in the base plate I!) and into a slotI25 formed in the release bar I23. Further a release dog 25 is pivotallymounted on a pin 25a carried by the base plate In and provided with twosubstantially rightangularly disposed legs I33a and I33b. The leg I33bof the release dog 25 projects substantially parallel to the front edgeof the base plate I0 and toward the right behind the detent 24 while theleg I 33a of the release dog 25 projects toward the rear of the baseplate I and is provided with a downwardly extending portion projectingthrough an opening 25a formed in the base plate I0 and into a slot I32formed in the release bar I23.

After the primary magnet II has been operated to effect longitudinalsetting of the primary carriage I6 and the secondary magnet I2 has beenoperated to eiiect lateral setting of the secondary carriage I5, theswitching mechanism IIJIIA may be completely released by energizing thewinding of the first release magnet I3; whereby the armature I22 isattracted and rotated in the clockwise direction about the pivot pinI22a causing the release bar I23 to be slid longitudinally toward theright against the bias of the coil spring I25 due to the cooperationbetween the armature I22 and the slot I24 formed in the release bar I23.When the release bar I23 is thus operated, the release dog I 29 isrotated in the clockwise direction about the pivot pin I28a by virtue ofthe cooperation between the leg I 27 thereof and the slot I26 formed inthe release bar I23; and likewise, the release dog 25 is rotated in theclockwise direction about the pivot pin 25a by virtue of the cooperationbetween the leg I33a thereof and the slot I32 formed in the release barI 23. When the release dog I28 is thus operated the leg I29 thereofmoves the detent I30, as well as the pawl 81 outwardly, whereby thecorresponding teeth of the ratchet 93 are disengaged; and likewise, whenthe release dog 25 is thus operated, the leg I33b thereof moves thedetent 24, as well as the pawl I9 outwardly, whereby the correspondingteeth of the ratchet 23 are disengaged. When the teeth of the ratchet 93are thus disengaged, the coil spring II4 acting upon the rack 90 slidesthe rack 96 longitudinally toward the right back into its normallongitudinal position; whereby the rack 96 acting through the gears I02and I03 retract the secondary carriage I5 back into its normal lateralposition. Also at this time the camming surface I I2 carried by thelever II3 cooperating with the camming surface III carried on the rack96 releases the lever II3 permitting the coil spring I I8 to rotate thelever I I3 in the clockwise direction about the pivot pin II5; wherebythe latch Ill disengages the corresponding opening IIIa formed in thefront edge of the primary carriage I6. Accordingly, at this time, theprimary carriage I6 is released both by the latch I I1 and by the detent24 and the associated pawl I9. Hence the coil spring I36 acting upon theprimary carriage I6 moves it toward the left back into its normallongitudinal position. When the winding of the release magnet I3 is thendeenergized, the arm I22 is. released and the coil spring I25 retractsthe release bar I23 toward the left back into its normal longitudinalposition; whereby the release dogs I28 and 25 are again rotated in thecounterclockwise direction about the respective pins I280: and 25a. Thusthe leg I29 of the release dog I28 disengages the detent I30 and theassociated pawl 87; and likewise, the leg I 33b of the release dog 25disengages the detent 24 and associated pawl I9. At this time theswitching mechanism [00A is completely released, the secondary carriageI5 occupying its normal lateral position and the primary carriage I6occupying its normal longitudinal position.

On the other hand, after the primary magnet II has been operated toeifect longitudinal setting of the primary carriage I6, and thesecondary magnet I2 has been operated to effect lateral setting of thesecondary carriage I5, the switching mechanism IO0A may be partiallyreleased by energizing simultaneously the winding of the first releasemagnet I3 and the winding of the second release magnet I4. When thewinding of the second release magnet I4 is thus energized, the armatureI34 is attracted and pivoted about its pivot pin, not shown; whereby itcooperates with the slot I35 formed in the release bar I23 in theclockwise direction about the screw 2Il. More particularly, the releasebar I23 is pivoted in the clockwise direction about the screw 2II to thedotted position shown in Figs. 3A and 33; whereby the leg I33a of therelease dog 25 rides out of the slot I32 formed in the release bar I23.Accordingly, when the winding of the first release magnet I3 isenergized, the armature I22 is attracted efiecting sliding of therelease bar I23 toward the right away from its normal longitudinalposition while it occupies its pivoted position. Thus when the releasebar I23 is operated at this time, the release dog I28 is operated in themanner previously explained; however, the release dog 25 is not operatedsince the leg I33a thereof does not engage the slot I32 formed in therelease bar I23 by virtue of the operated position of the armature I34of the second release magnet I4. Accordingly, the operated release dogI28 eifects the release of the ratchet 33 and the rack 35; however, therelease dog 25 does not effect the release of the ratchet 23 and theprimary carriage I5. When the rack 35 is thus released and returnedtoward the right into its normal longitudinal position, the secondarycarriage I5 is retracted toward the front of the base plate I0 into itsnormal lateral position by virtue of the cooperation between the rackand the gears I02 and I03 and the cooperation between the racks I06 andI0? and the gears I02 and I 03. Subsequently, when the winding of thefirst release magnet I3 is deenergized, the armature I22 is released andthe release bar I23 is returned toward the left into its normallongitudinal position by the coil spring I25. At this time when thewinding of the second release magnet I 2 is deenergized the armature I34 is released causing the coil spring I25 to rotate the release bar I23in the counterclockwise direction about the screw 2II; wherebythe leg I33a. of the release dog 25 reenters the slot I32 formed in the releasebar I23.

In view of the foregoing it will be understood that after the switchingmechanism IO0A has been operated in the event only the winding of therelease magnet I3 is energized, the secondary carriage I5 is releasedand returned to its normal lateral position and .then the primarycarriage i6 is released and returned to its normal longitudinalposition. However, after the switching mechanism IIlIIA has beenoperated in the event both the winding of the first release magnet i3and the winding of the second release magnet i i are simultaneouslyenergized, only the secondary carriage I5 is released and returned toits normal lateral position, the primary carriage It being retained inits operated longitudinal position. This arrangement is veryadvantageous in view of the fact that either a complete release or apartial release of the switching mechanism IO0A may be obtained byselective energization of the windings of the first release magnet i3and the second release magnet M as explained above. The complete releaseof the switching apparatus IBM is effected at any time when this 11 endis desired whereas, the partial release of the switching apparatuslflDAmaybe effectedin con junction with a trunk-hunting operation. v Forexample, supposethat a group of trunks extendns tea? 3-. tt li ei rp nteein. w adja en q nteets e qh 21 h eeteet b et m, t directory n mbermight qu re Op etion oi. the primary carriage i6 three steps andoperation of the secondary carriage I5 onestep. At this time theautomatic operation of the secondary carriage l5 is initiated; wherebyit may be operated nineadditional steps in the event all of thetrunks inthe first section of the contact bank 200 are busy. Accordingly the eeqee arr I5 is then released edt e P im .Qarriage ..i ...P? d additionalstep. Thereafter, thesecondary carriageIS is ope ted on s et pen ut matier tignthereof is initiated to co mplete the trunkhunt'ng operation inthe second section of the contactbank 2M. Qi course, the ultimaterelease the switching apparatus I"I III;A takes ones when boththesecondary carriage i5 and en the iim rr e ii are i ee Further theswitchingniechanism [60A comprisesprimary controlcontact structure 32including an insulating base plate 82a secured to the reset surface ofthe central portion of the apron I06 of the base plate It] adjacent tothe rear edge thereof by apart of bolts I42 extending throughopeningsformed in the apron Nb: and carrying nuts I42a on the outerthreaded shanks thereof. Also the structure 82 comprises two insul'a ngbushings I46 surrounding the bolts I42 and a conducting guide rail Iextending therebetween. e gues -s11 no is disposed below the insulatingbase plate 62d, carries longitudinally slidable wiper structure [3?including two mawmusr wipers 38' and 139' and aconnecting' insulatorI44. A m gma is secured to' th,insulat or I44 and surrounds the guidethe i e I Pr id with W dow 'wardly extendingtabs I330; embracing thesides of the guide rail I40 l3urther the insulating base plate 62a cf'ries a series of ten longitudinally spaced apartcantaets i4l cooperating with the wiper I 39; the individual contacts I II being spaced apartlongitudinally distances corresponding tothe respective steps of theprian In; and

rnary carriage Iii in the longitudinal direction.

Finally, the insulator I44 comprises two tabs i44a arranged in spacedapart relation and re ceiving two lugs I45 secured to the lower flange"IZ-b' of the bracket, 12. The wiper structure i3? occupies a normallongitudinal position when the primary carriage I6 occupiesitsnormallongn tudinal position; and when theprimary carriage I6 is movedstep by step away from its normal longitudinal position toward theright,the wiper structure I31 is likewise moved away from its normallongitudinal position step step toward the right. As noted above, thelongitudinal spacings of the individual contacts I4I correspond to thesteps of the primary carriage I6; whereby the wiper I39 engages a givenindividual contact l4l when the primary carriage l6 occupies itscorresponding longitudinally stepped position. Finally, the wiper I38engages the guide rail I40 at each step Of the wiper structure I31. Thusit will be understood that the guide rail i40 may be selectivelyconnected to the individual cohtacts l4l at the corresponding individualsteps of the primary carriage [5; which arrangement may be, employedforcontrol and supervisory purposes in an obvious manner.

asser 12" matter as switching' mediates rot prises two sets of controlswitch springs 3'I and as that may he s 1eeu e1y operated in anylongitudinally stepped position over the primary carriage 15 as desiredMore particularly, a link 46;

is secured to the primary bar IIi a by a screw fl and is mounted forlongitudinal sliding move ment with the primary carriage I6 by anarrangernent including a guide roller 4|. The set of switch springs 3|is mounted upon a bracket 44 by suitable intervening insulating strips;which bracket 44 is suitably secured tothe lefthand upper surface of thebase plate IQ. Like:

i wise the set of switch springs 35 is mounted upon a bracket 43 bysuitable intervening insulating strips; which bracket 43 is suitablysecured to the left-handupper surface of the base plate III. The bracket44 carries a pivot pin 34 upon which a bell-crank 32 is mounted; thebell-crank 32 comprising an arm 32a that cooperates with a roller 39carried by the lower side of the link 49 and an arm 32b that cooperateswith an insulator 33 arranged to operate the individual switch springs3! in the set 3|. Similarly, the bracket 43 carries a pivot pin 48 uponwhich a bell-crank 36 is mounted; the bell-crank 36 comprising an arm36a that cooperates with a roller 38 carried by the upper side of thelink 40 and an arm 36b that cooperates with an insulator 31 arranged tooperate the individual switch springs in the set 35. The rollers 39 and38 may be secured in any one or ten holes spaced longitudinally alongthe link 40 in order that the sets of switch springs 3! and 35 may beoperated at any desired longitudinal stepof the primary carriage l6. Asill'ustrated, the rollers 39 and 38 are respectively arranged in theseventh and first holes mentioned formed in the link 40. Accordingly,whenthe primary carriage I6 is stepped into first longi'- tudinalposition, the roller 38 engages the arm 35a of the bell-crank 36operating the set of switch springs 35. Similarly, when the primarycarriage I6 is stepped into its seventh longi tudinal position, theroller 39 engages the arm 32a of the bell-crank 32 operating the set ofswitch springs 3|.

Als o the switching mechanism I 06A cornprises a Set o f off-normalswitch springs 53 that is operated when the primary carriage I5 isstepped away from its normal longitudinal position; specifically,- theset of switch springs 53 is mounted upon a bracket 54 by suitablemartening insulating stripsj which bracket 54 suitably secured to theleft-hand upper surface of the baseplate I0. The bracket 54 carries apivot pin 56 upon which a bell-crank 55 is mounted;' the bell-crank .55comprising an arm 55a that cooperates with a roller 59 carried by theprimary bar I50, and an arm 55b that cooperates with an insulator 5'!arranged to operate the individual switch springs in the set 53.Accordingly, when the primary carriage I6 is stepped away from itsnormal longitudinal position, the roller 59 disengages the arm 55a ofthe bell-crank 55; whereby the arm 55b thereof operates the set ofoff-normal switch springs 53. Further, the switching mechanism IOOAcomprises a, set of impulsing springs 50 mounted upon a bracket 52 bysuitable, intervening insulating strips; which bracket 52 is suitablysecured to the lefthand upper surface or the base mate I0. Each time theprimary magnet II effects operation of the armature H, the armature I1engages an insulator 5| that operates the individual switch springs atis set so; measures, as the stimary magnet I is operated and. restored,the set of impulsing springs 59 transmits a corresponding series ofimpulses.

Further the switching mechanism I99A coinprises two sets of limit switchsprings 99 and 99 respectively mounted upon two brackets 99a and 99b bysuitable intervening insulating strips; the brackets 99a and 9% beingsuitably secured to the right-hand upper surface of the base plate !9.The bracket 99?) carries a pivot pin 99c supporting a bell-crank 98; andsimilarly, the bracket 99a carries a pivot pin 99d supporting abell-crank 98. The bell-crank 98 comprises an arm 98a that cooperateswith a roller 9! carried by the fixture 94 mounted on the rack 96 and anarm 98b that cooperates with an insulator 99c arranged to operate theindividual switch Springs in the set 99. Likewise, the bell-crank 98'comprises an arm 98d that cooperates with the roller 9! carried by thefixture 94 mounted on the rack 33 and an arm 98c that cooperates with aninsulator 98] arranged to operate the individual switch springs in theset 99'. When the rack 93 is stepped away from its normal longitudinalposition, the roller 9'! disengages the arm 98a of the bracket 98,whereby the arm 9% thereof causes the insulator 980 to operate the setof limit switch springs 99. When the rack 99 is stepped away from itsnormal longitudinal posi-- tion ten steps, the roller 91 engages the arm98d of the bell-crank 98' causing the insulator 98 to operate the set oflimit switch springs 99.

Further the switching mechanism I99A com prises a set of impulsingswitch springs 2w mounted upon a bracket 2|9a by suitable interveninginsulating strips; which bracket 2l9a is suitably secured to theright-hand upper surface of the base plate I9. Each time the secondarymagnet I2 effects operation of the armature 85, the armature 85 engagesan insulator 2I9b that operates the individual switch springs of the set2l9. Accordingly, as the secondary magnet I2 is operated and restoredthe set of impulsing springs 2l9 transmits a corresponding series ofimpulses. Finally, the switching mechanism I99A comprises a set ofswitch springs 2! 8 mounted upon a bracket 2l8a by suitable interveninginsulating strips; which bracket 2 8a is suitably secured to theright-hand upper surface of the base plate !9. Each time the firstrelease magnet !3 effects operation of the armature 22, the armature E22operates through a tie 229, an ininsulator 2 I 81) that operates theindividual switch springs of the set 2l8. Accordingly, as the firstrelease magnet i3 is operated and restored, the set of impulsing springs2! 8 is operated.

Reconsidering briefly the operation of the switching mechanism I99A, itwill be understood that the primary magnet is selectively operative toimpart selective longitudinal operation to the primary carriage l6 andthat the secondary magnet I2 is selectively operative to impartselective lateral operation to the secondary carriage !5. When thesecondary carriage i is thus operated, the two wiper sets are thrust anumber of steps into the contact bank, corresponding to the operation ofthe secondary magnet !2, in the two groups of contacts, corresponding tothe operation of the primary magnet whereby the two corresponding linesin the two corresponding ten line groups are selected. One of the twolines res ectively selected by the two wiper sets may be selected byexternal relay circuits, not shown. Subsequently, the switchingmechanism !99A .may be completely. released l4 utilizing the firstrelease magnet l3 or it may be only partially released utilizing boththe first release magnet !3 and the second release magnet !4 aspreviously explained.

Considering now the construction and arrange ment of the contact bank299 in greater detail, it will be observed, as shown in Figs. 7 to 9,inclusive, that each of the four sections of the contact bank 299comprises an assembly of ten individual contact units 29! retained inassembled relation by a plurality of bolts 2! 5. Specifically, eachcontact unit 29! comprises a centrally disposed insulating body 22! inthe form of a fiat strip having ten laterally spaced apart grooves 222formed in the front surface thereof and ten laterally spaced apartgrooves 223 formed in the rear surface thereof, the grooves 222 and 223being arranged in superimposed pairs. Ten individual fiat stripconductors 224 are arranged in the ten grooves 222; and likewise, tenindividual fiat strip conductors 225 are arranged in the grooves 223.The strip conductors 224 and 225 are retained in place in the respectivegrooves 222 and 223 by a series of vertically spaced apart clamps 239.Each of the clamps 239 comprises front and rear insulating sheets 23!and 232 overlying the respective surfaces of the strip conductors 224and 225, front and rear clamping plates 233 and 234, and two interveningspacing blocks 23% and 236. Finally, the elements of each clamp 239 areretained in assembled relation by two eyelets 23? and 238 respectivelyextending through the spacing blocks 235 and 236, as well as theadjacent ends of the clamping plates 233 and 233 and the adjacent endsof the insulating sheets 23! and 232. The eyelets 23'! and 238 are ofthe hollow variety having an opening extendingtherethrough adapted toreceive the clamping bolts 2&5 previously noted; whereby ten of thecontact units 29! may be securely retained in stacked relation. Thethicknesses of the insulating sheets 23! and 232 and the clamping plates233 and 234 are such that the bodies 22! of each two adjacent contactunits 29! are spaced longitudinally from each other a distancecorrespond ing to one longitudinal step of the primary carriage [6 ofthe switching mechanism !99A so that when the ten assembled contactunits 29! comprising a section in the contact bank 299 are supported bythe associated supporting structure adjacent to the switching mechanism199A, the contact strips 224 and 225 carried by the bodies 22! arespaced longitudinally corresponding to the various longitudinal steppedpositions of the two associated main wipers carried by the sec-- ondarycarriage 15. Also it is noted that the clamps 39 are spaced verticallyapart in order to define a plurality of effective contact sections ofeach contact unit 29! therebetween that are, in turn, respectivelyaccessible to the various wiper sets of the various switching mechanisms!99A, etc., arranged in the vertical tier in the supporting structure.Accordingly, the sections of the contact strips covered by the clamps239 constitute connecting multiples between the effective contactsections thereof that may be employed for marking purposes between thewiper sets of the various switching mechanisms having access thereto.

Finally, each contact unit 29! comprises a ter-- minal 249 including acentral body 24!, front and rear insulating sheets 242 and 243, frontand rear clamping plates 244 and 245, a top spacing block 246 and leftand right spacing blocks 24'! and 248.- Further, the element of theterminals 249.arere'-.-

ago-re a n" l taind in place by means of a plurality or hollow eyelets249 of the type previously mentioned; The individual contact strips 224extend between the insulating body 24! and the insulating sheet 262being disposed in suitable grooves formed in the associated surface ofthe insulating body 24!. Likewise, the individual contact strips 225extend between the insulating body MI and the insulating sheet 243 beingdisposed in suitable grooves formed in the associated surface of theinsulating body 2. As shown in Fig. 8, the first five contact strips 224on the right-hand front side of the contact unit 2M extend upwardly andthen to the right in the terminal z lu'and terminate upon forwardlyprojecting tails 224a; while the second five contact strips 224 on theleft-hand front side of the contact unit 20 I' extend upward-- ly andthen to the left in the terminal 240 and terminate upon forwardlyprojecting tails 2241). Similarly, the first five contact strips 225 onthe -right-hand rear side of the contact unit 20! extend upwardly andthen to the right in the terminal 240 and terminate upon rearwardlyprojecting tails 225a; While the second five contact strips 225 on theleft-hand rear side of. the con tact unit 20! extend upwardly and to theleft in the terminal 240 and terminate upon rearwardl'y projecting tails2252). On the right-hand side of the terminal 240 the forwardlyprojecting tails 224a and the rearwardly projecting tails 225a arestaggered upwardly toward the top spacer block 246 in order to provideadditional clearance for the soldering thereto of the terminated lines;likewise on the left-hand side of the terminal 240 the forwardlyprojecting tails 2241a and the rearwardly projecting tails 22512 arestaggered upwardly toward the top spacer block 246 in order to provideadditional clearance for the soldering thereto of the wires of theterminates lines.

Recapitulating, it is pointed out that the switching mechanisms lllOA,etc., are carried by the supporting structure, including the elements 2|la, 2| lb, 21-2, 2l3, etc., in vertically stacked relation in what maybe termed the Z direction. Likewise, the contact bank 290 extendsvertically providing adjacent sections spaced apart substantially thefixeddistance Z in the Z direc-' tion and accessible to the respectiveswitching mechanisms. In each section of the contact bank 209, the tenindividual contact units 2M are spaced longitudinally apartsubstantially the fixed distance X in the X direction and correspondingto the longitudinal steps of the primary carriages of the switchingmechanisms 100A, etc. Further, the four sections of the contact bank 200are spaced longitudinally apart corresponding to the distances betweenthe various pairs of wipers in the two Wiper sets of the switchingmechanism lilflA, etc. Finally, in each contact unit 20!, the individualcontact strips 224, as well as the individual contact strips 225, arespaced apart laterally the substantially fixed distance Y in the Ydirection corresponding to the lateral steps of the secondary carriagesof the switching mechanisms 100A, etc.

In view of the foregoing, it is apparent that there has been providedswitching apparatus comprising a plurality of improved switchingmechanisms and an improved contact bank assembly commonly associatedtherewith.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all 16 such modifications as fall within the truespirit and scope of the invention.

What is claimed is:

l. A contact bank assembly for a plurality of automatic switches stackedin the Z direction, adjacent ones of the switches being spaced-apart asubstantially fixed distance Z in the Z direction, each of the switchesbeing capable of coordinate step-by-step movements in the X and Ydirections, in eacn of the switches each X step being a substantiallyfixed distance X and each Y step being a substantially fixed distance Y;said contact bank assembly comprising a plurality of contact unitsstacked in the X direc-' tion and extending in the Z direction; each ofsaid contact units including a flat insulating body having a pluralityof grooves formed in one surface thereof and extending'in the Zdirection, adjacent ones of said grooves being spaced apartshbstantially said fixed distance Y in the Y direction, a plurality ofcontact strips respectively positioned in said grooves, and a pluralityof clamping elements securing said contact strips in place in saidgrooves, adjacent ones of said clamping elements being spaced apartsubstantially said fixed distance Z in the Z direction; and meansincluding members extending through aligned openings provided inengaging ones of said clamping elements for clamping together engagingones of said clamping elements car ried by said contact units, engagingones of said clamping elements carried by adjacent ones of said contactunits spacing apart said adjacent contact units substantially saidfixeddistance in the X direction.

2. A contact bank assembly for a plurality of automatic switches stackedin the Z direction, adjacent ones of the switches being spaced-apart asubstantially fixed distance Z in the Z direction, each of the switchesbeing capable of coordinate step-by-step movements in the X and Ydirections, in each of the switches each X step being a substantiallyfixed distance X and each Y step being a substantially fixed distance Y;

* said contact bank assembly comprising a plurality of contact unitsstacked in the X direction and extending in the Z direction; each ofsaid contact units including a flat insulating body having a firstplurality of grooves formed inone side thereof and extending in the Zdirection and a second plurality of grooves formed in the other sidethereof and extending in the Z direction, adjacent ones of said firstgrooves and adjacent ones of said second grooves being spaced apartsubstantially said fixed distance Yf in the Y direc tion, a firstplurality of contact strips respectively positioned in said firstgrooves, a second plurality of contact strips respectively positioned insaid second grooves, and a plurality of clamping elements securing saidcontact strips in place in said grooves, adjacent ones of said clampingelements being spaced apart substantially said fixed distance Z in the Zdirection; and means including members extending through alignedopenings provided in engaging ones of said clamping elements forclamping together engaging ones of said clamping elements carried bysaid contact units, engaging ones of said clamping elements carried byadjacent ones of said contact units spacing apart said adjacent contactunits substantially said fixed distance X in the X direction.

3. A contact bank assembly for a plurality of automatic switches stackedin the Z direction,

17 adjacent ones of the switches being spaced-apart a substantiallyfixed distance Z in the Z direction, each of the switches being capableof coordinate step-by-step movements in the X and Y directions, in eachof the switches each X step being a substantially fixed distance X andeach Y step being a substantially fixed distance Y;

said contact bank assembly comprising a plu- I rality of contact unitsstacked in the X direction and extending in the Z direction; each ofsaid contact units including a flat insulating body having a, pluralityof grooves formed in one surface thereof and extending in the Zdirection, adjacent ones of said grooves being spaced apartsubstantially said fixed distance Y in the Y direction, a plurality ofcontact strips respectively positioned in said grooves, and a pluralityof clamping elements securing said contact strips in place in saidgrooves, each of said clamping elements having a pair of openings formedtherein and spaced apart in the Y direction and positioned exteriorly ofthe edges of said fiat insulating body, adjacent ones of said clampingelements being spaced apart substantially said fixed distance Z in the Zdirection; and means including pairs of members extending throughaligned pairs of said openings for clamping together engaging ones ofsaid clamping elements carried by said contact units, engaging ones ofsaid clamping elements carried by adjacent ones of said contact unitsspacing apart said adjacent contact units substantially said fixeddistance X in the X direction.

4. A contact bank assembly for a plurality of automatic switches stackedin the Z direction, adjacent ones of the switches being spaced-apart asubstantially fixed distance Z in the Z direction, each of the switchesbeing capable of co ordinate step-by-step movements in the X and Ydirections, in each of the switches each X step being a substantiallyfixed distance X and each Y step being a substantially fixed distance Y;said contact bank assembly comprising a plurality of contact unitsstacked in the X direction and extending in the Z direction; each ofsaid contact units including a flat insulating body having a pluralityof grooves formed in one surface thereof and extending in the Zdirection, ad-

jacent ones of said grooves being spaced apart substantially said fixeddistance Y in the Y direction, a plurality of contact "stripsrespectively positioned in said grooves, means including a plurality ofpairs of clamping plates for securing said contact strips in place insaid grooves, the individual clamping plates of each of said pairs beingpositioned on opposite sides of said flat in sulating body and havingpairs of aligned openings formed therein and positioned exteriorly of,

the edges of said flat insulating body, and means including a pair ofhollow rivets extending between pairs of the aligned openings in saidpair of clamping plates for clamping in place said pair of clampingplates, adjacent ones of said clamping elements being spaced apartsubstantially said fixed distance Z in the Z direction; and meansincluding pairs of members extending through aligned pairs of saidhollow rivets for clamping together engaging ones of said clampingplates carried by said contact units, engaging ones of said clampingelements carried by adjacent ones of said contact units spacing apartsaid adjacent contact units substantially said fixed distance X in the Xdirection.

5. A contact unit comprising a longitudinally extending fiat insulatingbody, a first group of L-shaped grooves formed in the right-hand frontsurface of said body, a second group of L-shaped grooves formed in theleft-hand front surface of said body, a third group of L-shaped groovesformed in the right-hand rear surface of said body, a fourth group ofL-shaped grooves formed in the left-hand rear surface of said body, thestems of said first and second grooves extending longitudinally andbeing arranged in laterally spaced-apart relation and the stems of saidthird and fourth grooves extending longitudinally and being arranged inlaterally spaced-apart relation, corresponding ones of the stems of saidfirst and third grooves being arranged in alignment through said bodyand corresponding ones of the stems of said second and fourth groovesbeing arranged in alignment through said body, the arms of said firstand second grooves extending laterally and being arranged inlongitudinally spaced-apart relation and the arms of said third andfourth grooves extending laterally and being arranged in longitudinallyspaced-apart relation, corresponding ones of the arms of said first andsecond grooves being arranged in transverse alignment and correspondingones of the arms of said third and fourth grooves being arranged intransverse alignment, the arms of said first and third grooves beingstaggered with respect to each other in the longitudinal directionthrough said body and the arms of said second and fourth grooves beingstaggered with respect to each other in the longitudinal directionthrough said body, first and second and third and fourth groups ofL-shaped contact strips respectively positioned in said first and secondand third and fourth groups of grooves, the arms of said first and thirdcontact strips extendin laterally toward the right and the arms of saidsecond and fourth contact strips extending laterally toward the left,the outer ends of the arms of said contact strips proecting beyond theedges of said body and constituting terminals, front and rear insulatingsheets respectively positioned on said front and rear surfaces of saidbody and respectively covering the bends in said first and secondgrooves and the bends in said third and fourth grooves, front and rearclamping plates respectively positioned on said front and rear sheets, aplurality of sets of aligned openings being formed in said front andrear sheets and in said front and rear plates exteriorly of said body,and means including a plurality of members respectively extendingthrough said sets of openings for clamping said plates together.

6. The contact bank assembly set forth in claim 1, wherein said contactstrips incorporated in each of said contact units are fanned-outadjacent to one end of each of said contact units to providespaced-apart terminals accommodating soldered connections to externalconductors.

HANS SENGEBUSCH.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,103,623 Reynolds July 14, 1914 1,283,563 Roberts Nov. 5,1918 2,071,713 Terrill Feb. 23, 1937 2,239,329 Lindstrom Apr. 22, 1941

